The present invention relates to a method and apparatus for scaling of a laser system to higher power.
End-pumped solid-state lasers are highly efficient, high beam quality, coherent light sources. Typically, end-pumped lasers use a single diode or a single diode array light source so that the light from such source can be focused into a volume appropriate to the solid-state laser to be pumped. Use of such small scale sources is limited when scaling to high power, however, by the inability to efficiently focus more than only a few of such devices into the fundamental transverse laser mode.
Power scaling of pumping light sources may be accomplished with various techniques. For example, polarization coupling may be used in which two orthogonally polarized beams from diode lasers or diode laser arrays are combined at a polarizing beam splitter and then this combined beam is focused into the solid-state laser medium. Another technique is to use fiber bundles to bring light from many laser diodes, which can be presented in a nominally colinear manner into the solid-state laser axis, to achieve end-pumping. In any case, it is desired to increase pump power and to efficiently focus the pump beam into the gain medium for a higher power output.
Conventionally, a laser mode is defined by the optics of the optical resonator in a laser oscillator, or by the beam that is amplified in a laser amplifier.